# Applying Dict to DataFrame column

**URL:** <https://discourse.julialang.org/t/applying-dict-to-dataframe-column/6397>\
**Category:** General Usage\
**Created:** [October 11, 2017, 11:21pm UTC](https://discourse.julialang.org/t/applying-dict-to-dataframe-column/6397 "2017-10-11T23:21:33Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![John\_Gibson](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/john_gibson/32/5321_2.png) [@John\_Gibson](https://discourse.julialang.org/u/John_Gibson)\
**Post date:** [October 11, 2017, 11:21pm UTC](https://discourse.julialang.org/t/applying-dict-to-dataframe-column/6397/1 "2017-10-11T23:21:33Z")

</div>

I figured out a way to use Dict to do some text processing on Strings within a DataFrame, but I suspect there’s a better way to do it.

```julia
shell> cat benchmarks.csv
c,iteration_mandelbrot,0.263798
c,recursion_fibonacci,0.024076
julia,iteration_mandelbrot,0.167139
julia,recursion_fibonacci,0.040278
lua,iteration_mandelbrot,0.104
lua,recursion_fibonacci,0.026

julia> using DataFrames

julia> benchmarks = readtable("benchmarks.csv", header=false, names=[:language, :benchmark, :time])
6×3 DataFrames.DataFrame
│ Row │ language │ benchmark │ time │
├─────┼──────────┼────────────────────────┼──────────┤
│ 1 │ "c" │ "iteration_mandelbrot" │ 0.263798 │
│ 2 │ "c" │ "recursion_fibonacci" │ 0.024076 │
│ 3 │ "julia" │ "iteration_mandelbrot" │ 0.167139 │
│ 4 │ "julia" │ "recursion_fibonacci" │ 0.040278 │
│ 5 │ "lua" │ "iteration_mandelbrot" │ 0.104 │
│ 6 │ "lua" │ "recursion_fibonacci" │ 0.026 │

julia> dict = Dict("c"=>"C", "julia"=>"Julia", "lua"=>"LuaJIT");

julia> for i in 1:size(benchmarks)[1]
           benchmarks[i,1] = dict[benchmarks[i,1]]
       end
                                                                                                                            
julia> benchmarks
6×3 DataFrames.DataFrame                                                                                                    
│ Row │ language │ benchmark │ time │                                                                      
├─────┼──────────┼────────────────────────┼──────────┤                                                                      
│ 1 │ "C" │ "iteration_mandelbrot" │ 0.263798 │                                                                      
│ 2 │ "C" │ "recursion_fibonacci" │ 0.024076 │                                                                      
│ 3 │ "Julia" │ "iteration_mandelbrot" │ 0.167139 │                                                                      
│ 4 │ "Julia" │ "recursion_fibonacci" │ 0.040278 │                                                                      
│ 5 │ "LuaJIT" │ "iteration_mandelbrot" │ 0.104 │
│ 6 │ "LuaJIT" │ "recursion_fibonacci" │ 0.026 │

```

Any suggestions to replace the for loop?

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<div class="post-metadata">

**Author:** ![cstjean](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/cstjean/32/1444_2.png) [@cstjean](https://discourse.julialang.org/u/cstjean)\
**Post date:** [October 12, 2017, 12:25am UTC](https://discourse.julialang.org/t/applying-dict-to-dataframe-column/6397/2 "2017-10-12T00:25:09Z")

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Something like `benchmarks[:language] = [dict[lang] for lang in benchmarks[:language]]`?

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<div class="post-metadata">

**Author:** ![John\_Gibson](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/john_gibson/32/5321_2.png) [@John\_Gibson](https://discourse.julialang.org/u/John_Gibson)\
**Post date:** [October 12, 2017, 2:34am UTC](https://discourse.julialang.org/t/applying-dict-to-dataframe-column/6397/3 "2017-10-12T02:34:05Z")

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Thank you! I actually formulated something close to the right-hand-side of that expression but found that its type was `Array{String,1}` and didn’t have faith that it would play nice with the type `DataArrays.DataArray{String,1}` on the LHS.